Propeller and method of making the same



Sept, 1111, 1923. 11,467,785

L. T. FREDERICK PROPELLERAND METHOD OF MAKING THE SAME Filed DeC. 50, 1918 WITNESSES: INVENTOR Memes LOUIS T. FREDERICK, 0F WILKINSBURG,

PENNSYLVANIA, KSSIGNOB, TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- I VANIA.

Application filed December 30, 1918.

combining unusual strength and durability I with exceptional lightness.

The wooden propellers now in use are relatively heavy and are also objectionable on account of the fact that they will warp and crack or' splinter because of climatic changes. Furthermore, the wood rapidly becomes pitted during the use of the propeller so that it is not only weakened but its surface is roughened until it offers a materially increased resistance to the air.

Propellers have been constructed and successfully employed composed of superimposed layers of fibrous sheet material impregnated with a hardened binder, of proper character, such as a phenolic condensation product. My present invention resides in the construction of a propeller of this character which shall be hollow in construction, rather than solid, to. insure lightness without unduly weakening its strength.

A still further object of my invention resides in the provision of a convenient method for assembling and curing a propeller of this character, I

With these and other objects in view, my invention will be' more fully described, illustrated in the drawings, in the several views of which corresponding numerals indicate like parts, and then particularly pointed out in the claims.

Fig. 1 is a plan view of a core about which a propeller may be formed; Fig. 2 is a corresponding view showing the manner of applying certain layers of the sheet material to the core, the intended outline of the finished ropeller body being shown in broken lines; ig. 3 is a side elevation of the structure shown in Fig. 2; Fig. 4 is a transverse sectional view taken substantially on the line IVIV of-Fig. 2, and Fig. 5 is a plan view of the finished propeller.

In practicing my invention, I may assem- PROPELILER AND METHOD OF MAKING: THE SAME.

Serial No. 268,952.

ble fibrous material impregnated with a suitable binder about a core, of such nature that it may be ultimately removed from the finished propeller, and may cure the material thus assembled in a proper manner, dependent upon the type of the binder employed, to form a propeller, after which I may remove the core.

Preferably, in order to facilitate its removal, I employ a core of a material which is capable of fusing or melting at a relatively low temperature so that the finished propeller may be tapped and the fused core may be drained from it. In a copending application filed by Chester 1. Allcutt October 8, 1917, Serial No. 195,262, and assigned to the Westinghouse Electric & Manufacturing Company, is disclosed the employment of cores of this character for forming hollow bodies of fibrous material and a binder, capable of hardening under heat and pressure, and the utilization of such a core constitutes no part of my present invention. While the fibrous material may be in any desired form and may be applied to the core in any suitable manner, I prefer to follow the method disclosed by me in a copending application filed Dec. 30, 1918, Serial No. 268,953, which, briefly stated, is as follows: A plurality of layers of suitable shapes and sizes are cut from a sheet of fibrous material, such as duck, paper. or cotton batting, which has been impregnated with a suitable binder, as, for example, a phenolic condensation product. These layers are of such shapes and sizes that, when superimposed in proper relative positions, they will form a body having substantially the shape of the desired propeller. Furthermore, certain of these layers have openings cut in them so that, when they are thus assembled, the body formed is hollow having a chamber corresponding in shape to the shape of a core to be employed. In the above-referred-to application filed by me, a core of wood or other suitable material is utilized and becomes a permanent portion of a propeller. In the present instance, I may employ a core 1 of any suitable material which will melt at the proper temperature, certain alloys being particularly desirable for this purpose as, for example, an alloy comprising two parts of bismuth, one part of tin and one part of lead and melting at about 98 C. The core preferably corresponds, in

ings, and the layers 2 of any suitable fibrous shape, to the desired .shape of the propeller, as best indicated in Figs. 1 to 4 of the drawsheet material, impregnated with the desired binder, are superimposed in proper relative positions in such manner as to completely enclose the core and form a shell of proper thickness about it, this assembling being possible since certain of the layers are formed with openings 3-which, when the layers are superimposed, will provideacore-receiving chamber.

' After the body has been assembled in this manner, it is positioned in a mold and there -to subject the fibrous material to heavy pressure between it and the walls of the I closed mold. This pressure may be applied to the core by any suitable means, as by a plunger forced into the chamber containing the molten core. However, I prefer to apply the pressure by pumping, in a molten state, additional material, of the same character as that constituting the core, into the chamber.

After the curing is completed, the still molten core may be drained from the shell constituting the finished propeller through the opening through which pressure has been applied and which is preferably formed through one or both of the hub faces.

While the core employed may vary in v size and shape for any given propeller, ac

cording to the desired thickness of the propeller walls,-care should be taken that the I core be symmetrically formed in order that the propeller, molded by employing it, may be symmetrically formed and balanced when finished. As the core is in a molten state during the curing of the propeller.

body, itis possible to employ a core slightly under-sized and to depend upon the supply of added core-forming material, as a pressure-applying means during the curing, to

completely fill theconcavi ty of the propeller. bling of the material about the core and also the positioning of the assembled body and its enclosed core in the mold.

Furthermore, by applying pressure from within, by means of a fused or molten core,

This will obviously facilitate assem it is possible to secure great 'uniformityin the finished product, as there is not the same tendency toward wrinkling or displacing of the fibrous sheet material during molding that there is when pressure is applied directly to the outside of the propeller body.

After the propeller body has been finished a suitable metallic hub maybe fitted to it in any manner desired or, if preferred, *means may be provided for molding a hub of metal or other suitable material into the propeller body'while the latter is being.

molded..

As numerous changes, both in the details of the propeller construction and in the, manner of assembling and curing it are obviously possible, no limitations are to'be imposed upon my invention other than those indicated in the appended claims.

I claim as my invention:

1. A propeller comp-rising a-hollow pro peller-shaped shell of fibrous material impregnated wth a hardenedbinder.

2. A propeller comprising a hollow propeller-shaped shell of fibrous material impregnated with a hardened phenolic condensation product.

3. A, propeller comprising a hollow pro- Y peller-shaped body of superimposed layers of fibrous sheet material impregnated with a hardened binder. I

4. A propeller comprising a hollow propeller-shaped body of fibrous sheet material impregnated with a hardened binder, in

which the sheets are disposed in superimposed parallel relation.

5. A propeller comprising a hollow propeller-shapedbody of superimposed layers of fibrous sheet material impregnated with a hardened binder, in which the layers are disposed substantially parallel to the faces ofthehub.

In testimony whereof, I have hereunto subscribed my name this 21st day of Dec., 1918.

LOUIS T. FREDERICK. 

